There has been a preference option NoMACinUUID for those who do not
wish to have their MAC address embeded in the documents; I just did
not get to producing a GUI for setting. I am not sure how strong
people feel about this as a privacy issue: if the feelings are strong
we could make no-MAC the default, or, if the feelings are very
strong, we could remove it altogether (I am not greatly in favour of
the last one).

Joaquine is right; from Win2k MS no longer uses MAC generated uuid's;
they now fill the GUID bits randomly and call this 'version 4' uuid --
there is only one problem with this, namely, it is not an uuid, it is
a random number.